[Analysis and Characterization of Multi-modified Anodes via Nitric Acid and PPy/AQDS in Microbial Fuel Cells]

The properties of anode material are crucial for high performances in microbial fuel cells (MFCs). Hereby, a biocompatible, conductive, and high electron transfer ability anode was fabricated by electrodepositing polypyrrole/anthraquinone-2, 6-disulphonic disodium salt (PPy/AQDS) onto nitric acid-soaked carbon felt. The results showed that the multi-modified anode outperformed the pristine one in biomass, electrical conductivity, and exchange current density with between 2.4 and 3.3 times better performance. The multi-modified anode (applied with 0.12 C·cm^-2 total charge density) showed the highest peak current density (2.86 mA), the largest amount of biomass loading (0.44 mg·cm^-2), the most favoured electrical conductivity (0.33 S·cm^-1), and exchange current density (3.65×10^-3 A·m^-2), as a result, the maximum power density of the MFC equipped with the anode delivered a 2.2-fold increase over that of the control (1060.7 mW·m^-2vs. 477.6 mW·m^-2), and thus has great potential to be used as an anode for high-power MFCs. Further investigation revealed that the increased energy output might be attributed to the bridging of the carbon fibers by electrically conductive PPy/AQDS composite films, which provided a uniform connection throughout the nitric treated carbon felt as well as the synergetic effects between the newly formed functional groups like pyrrolic N and PPy/AQDS. It was proposed that integrating biocompatibility (BCB) with electrical conductivity (EC) and electron transfer efficiency (ETE) through multi-modification could form high-performance anode. Future efforts to be made for realizing more extraordinary high-performance MFCs anodes were also outlined. This work may also provide a novel universal approach for the development of other types of anode for high-performance MFCs through integrating the BCB with EC and ETE simultaneously.